This invention relates to display devices, and particuarly to thin film electroluminescent display panels.
Light emitting display devices have been fabricated utilizing the electroluminescent effect obtained by exposing special light-emitting materials (sometimes called phosphors) to an electrical field (see, for example, U.S. Pat. No. 4,342,945).
Phosphors have been found which give off different colors, and attempts have been made to use several phosphors to make a multicolor display. A common approach has been to stack layers of different phosphors to obtain several colors (for example, R. E. Coovert, et al., "Feasibility of a Dual-Color ACTFEL Display, SID Dig., 1982, pp. 128-129). In a paper by A. H. Kitai and G. J. Wolga, it was suggested that multicolor devices might be provided by using spatially-modulated activator doping by means of laser photochemical vapor deposition ("Two-Color Thin-Film Electroluminescence with Spatially-Selective Activator Doping", SID 83 Digest, pp. 138-139). Other investigators have shown that ZnS could be implanted with Mn ions to make electroluminescent films. However, the overall surface was implanted rather than discrete locations on the film (A. J. Warren, et al, "A Study of the Luminescent and Electrical Characteristics of Films of ZnS Doped with Mn", Journal of Luminescence 28 (1983), pp. 147-162 and A. J. Warren et al, "The Effect of Mn Concentration on the Photoluminescence of ZnSMn", J Phys. D: Appl. Phys. 16 (1983), pp. 225-232).